Delta coder

Claim 2

A delta modulator comprising: a reference signal source (30); a clock signal source (14, 35); a comparator digitizer means (10, 13-21) including: means (10, 13, 15, 16, 31) coupling the reference and clock sources for providing a relative magnitude indication between an applied analog signal magnitude sampled at the clock rate and the level of the reference signal; and means (17-21) for providing a first digital signal indication (20) for each analog magnitude exceeding the reference level, and for providing a second digital signal indication (21) for each analog magnitude not exceeding the reference level; and a digital to analog converter in feedback relation to the comparator digitizer and including: reference level setting means (22-29) coupling the reference source for selectively and incrementally varying the reference level in a first and second magnitude direction responsive to first and second digital signal indications respectively; and means (3, 32-38) coupling the reference level setting means for non-linearly varying the reference level at a first time rate of change in the magnitude direction corresponding to each digital signal and for non-linearly varying the reference level at a second time rate of change responsive to the detection and duration of a succession of N identical digital signals in a magnitude direction corresponding herewith.

Claim 3

In a delta modulation encoder according to claim 1, wherein the means for non-linearly varying the refErence level includes means (34) for exponentially varying said level.

Claim 4

A delta modulator comprising: a reference signal source (30); a clock signal source (14-35); a comparator-digitizer means (10, 13-21) including: means (10, 13, 15, 16, 31) coupling the reference and clock sources for providing a relative magnitude indication between an applied analog signal magnitude sampled at the clock rate and the level of the reference signal; and means (17-21) for providing a first digital signal indication (20) for each analog magnitude exceeding the reference level, and for providing a second digital (21) for each analog magnitude not exceeding the reference level, and a digital to analog converter in feedback relation to the comparator digitizer and including: reference level setting means (22-29) coupling the reference source for selectively and incrementally varying the reference level in a first and second magnitude direction responsive to first and second digital signal indications respectively; and means (32) responsive to a succession of N identical digital signal indications for generating a first control signal for the duration of the succession of at least N signals and for generating a second control signal otherwise; means (37, 34, 35) for producing a sequence of pulses whose relative widths vary exponentially in one direction at a first time rate of change responsive to the first control signal, and whose relative widths vary exponentially in the other width direction at a second time rate of change responsive to the second control signal; and means (22-29) for incrementally varying the reference level proportional to the variation in successive pulse widths and in the magnitude direction associated with the corresponding digital signal indications.

Claim 5

A delta modulator comprising: a reference signal source (30); a clock signal source (14-35); a comparator-digitizer means (10, 13-21) including: means (10, 13, 15, 16, 31) coupling the reference and clock sources for providing a relative magnitude indication between an applied analog signal magnitude sampled at the clock rate and the level of the reference signal; and means (17-21) for providing a first digital signal indication (20) for each analog magnitude exceeding the reference level, and for providing a second digital (21) for each analog magnitude not exceeding the reference level, and a digital to analog converter in feedback relation to the comparator digitizer and including: reference level setting means (22-29) coupling the reference source for selectively and incrementally varying the reference level in a first and second magnitude direction responsive to first and second digital signal indications respectively; and means (32) responsive to a succession of N identical digital signal indications for generating a first control signal for the duration of the succession of at least N signals and for generating a second control signal otherwise; means (37, 34, 35) for producing a sequence of pulses whose relative widths vary exponentially in one direction at a first time rate of change responsive to the first control signal, and whose relative widths vary exponentially in the other width direction at a second time rate of change responsive to the second control signal; and means (22-29) for incrementally varying the reference level proportional to the variation in successive pulse widths and in the magnitude direction associated with the corresponding digital signal indications.

Claim 6

A delta modulator according to claim 3, wherein the means for producing width-modulated pulse signals comprise a charge storage circuit (4-C2, T5) for charging through a first path (T5, C2) defining a first time constant responsive to the first control signals, and for discharging through a second path (C2, R1, R2) defining a second time constant responsive to the second control signal.

Claim 7

A delta demodulator comprising: a digital to analog converter for incrementally varying a first and second magnitude direction, an output signal magnitude level responsive to respective first and second digital signal indications; means (62, 64, 32) responsive to a succession of identical digital signal indications for generating a first control signal for the duration of the succession and for generating a second control signal otherwise; means (33, 38) for producing a sequence of pulses whose relative widths vary exponentially in one direction at a first time rate of change responsive to the first control signal and vary exponentially in the other width direction at a second time rate of change responsive to the second control signal; and means (65, 66, 67, 25-27, 50, 51, 30) for incrementally varying the output signal magnitude level proportional to the variations in successive pulse widths and in the magnitude direction associated with the corresponding binary signal indication.

Claim 8

A delta demodulator comprising: a digital to analog converter for incrementally varying a first and second magnitude direction, an output signal magnitude level responsive to respective first and second digital signal indications; means (62, 64, 32) responsive to a succession of identical digital signal indications for generating a first control signal for the duration of the succession and for generating a second control signal otherwise; means (33, 38) for producing a sequence of pulses whose relative widths vary exponentially in one direction at a first time rate of change responsive to the first control signal and vary exponentially in the other width direction at a second time rate of change responsive to the second control signal; and means (65, 66, 67, 25-27, 50, 51, 30) for incrementally varying the output signal magnitude level proportional to the variations in successive pulse widths and in the magnitude direction associated with the corresponding binary signal indication.